Which priest took the horn of oil and anointed Solomon king?

Answer: Zadok

Zadok the priest took the horn of oil from the tabernacle and anointed Solomon at Gihon, and the people shouted, 'Long live King Solomon!'

“Then Zadok the priest, Nathan the prophet, and Benaiah son of Jehoiada, along with the Cherethites and Pelethites, went down and set Solomon on King David’s mule, and they escorted him to Gihon.”— 1 Kings 1:38 (BSB)